Chrome and Firefox can reach localhost; Internet Explorer 9 can't. Why?

The title is pretty self explanatory. I have a Windows 7 environment with IIS7 installed. I'm sure this is the result of me mucking around with settings at some point. Trying to avoid a fresh Windows install.

Quick breakdown of what I've tried:

• Resetting IEs settings back to defaults.
• Using the IP address of the machine vs. localhost. Using the IP does work.
• Pinging localhost. I can, which isn't surprising because Firefox/Chrome have no problem resolving it.

Any other ideas?

After a bit more wasted time I realized I had clicked 'Restore advanced settings' earlier as opposed to the button under the more encompassing 'Reset Internet Explorer settings' similarly on the Advanced tab.

Once I did this my localhost once again works correctly.

Is localhost in the correct security zone for Internet Explorer? Security zone settings apply only to IE and several other Windows-specific applications, so this may explain this problem.